1. Field of the Invention
The present invention relates generally to unmanned underwater vehicles (UUV) used with submarines and, more particularly, to a laser based system for autonomous docking of the UUV to a submarine.
2. Description of the Prior Art
Optical docking systems have been utilized on space vehicles, robot and machine guidance systems, and in various types of autonomous UUV docking situations.
However, docking to submarines involves relative motion of water currents which affects the motion of both the submarine and the UUV. This can result in a relative motion for which difficulties arise in either establishing or maintaining a visual lock between a docking station on the submarine and the UUV. For example, the UUV and/or the submarine may move to relative positions where the bulk of the submarine blocks the optical signals on the docking station of the submarine.
Acoustic methods for docking underwater vehicles have also been documented. The spatial accuracy of underwater acoustic docking systems, although useful for long-range docking procedures, may be severely limited for close range docking maneuvers with the submarine.
The following United States Patents describe various prior art systems that may be related to the above and/or other docking systems:
U.S. Pat. No. 3,646,771 (issued Mar. 7, 1972) to Greene, discloses an underwater communicating connection between a marine vessel, such as a submarine, and a stationary structure, such as a dock or underwater caisson or another marine vessel, for the passage of personnel, which is formed by juxtaposing the vessel and structure to isolate a water-containing space between watertight doors on the vessel and structure, removing water from the space, and admitting air at subaqueous pressure, whereby the vessel is forced against the structure by hydrostatic pressure; the doors are then opened. A flexible sealing member outside of the connection on the vessel or structure may engage a sealing surface on the other for additional sealing. The dock may include a tower extending to the water surface. The vessel can be positioned by anchors resting on a platform or engaged to a frame fixed to the ground.
U.S. Pat. No. 4,799,825 (issued Jan. 24, 1989) to Meyerhoff et al, discloses a method for underwater fuel transfer of liquid fuels such as crude oil from an off-shore, stationary underwater mooring to a submerged submarine oil tanker. There is provided a berthing guidance and control system including permanently moored acoustic transponders interrogated by the tanker sonar equipment to provide input commands for azimuth control along the on-tack position in conjunction with speed controls. The system also includes an arrestor mooring apparatus for decelerating the tanker as the tanker approaches the underwater station. This underwater station has the dual function use of providing mooring for the tanker and also reception of the tanker oil transfer device.
U.S. Pat. No. 5,748,102 (issued May 5, 1998) to Barron, discloses an apparatus for interconnecting an unmanned underwater vehicle and a free-fitting communications pod that includes a communications cable depending from the pod and extending to a buoy of less buoyancy than the pod, such that the cable carries communication signals between the pod and the buoy and extends generally vertically in a column of water between the pod and the buoy, the buoy being in communication with a distal station. The apparatus further includes a mobile unmanned underwater vehicle having therein guidance means for directing the vehicle to the cable, the vehicle being in communication with a control vessel, connector means mounted in a nose portion of the vehicle and adapted to intercept the cable, the connector means being further adapted to permit the cable to slide therethrough as the vehicle continues movement after the intercept of the cable, and complementary alignment means on the vehicle and the pod adapted to cause the vehicle to engage the pod in a preselected orientation and azimuth, with the communication components of the UUV and pod in alignment, whereby to place the control vessel in communication with the distal station.
U.S. Pat. No. 6,502,527 (issued Jan. 7, 2003) to Danielson, discloses a system for recovering submerged devices that uses two recovery tubes of an underwater recovery vehicle. A recovery member is disposed within a first recovery tube. A second recovery tube receives the submerged device. To recover the submerged device, the recovery member is extended from the first recovery tube. A capture arm, which is pivotally attached to the end of the recovery member, is extended. The extended capture arm is engaged with the submerged device. The capture arm is adjusted to align the submerged device with the second recovery tube. The recovery member is retracted to recover the submerged device into the second recovery tube. Because the recovery member is not disposed within the same recovery tube that is used to house the retrieved submerged device, the submerged device may have an outer diameter approximately equal to the inner diameter of the recovery tube.
U.S. Pat. No. 6,677,889 (issued Jan. 13, 2004) to Van Rees et al, discloses an auto-docking system that can automatically dock a surface ship. The auto-docking system provides a close in radar system and a secondary propulsion system that is under control of a docking processor.
U.S. Pat. No. 7,025,014 (issued Apr. 11, 2006) to Forgach et al, discloses one or more docking cages releasably attached to a tow line extending from the stern of a retrieval surface ship, that emit optical tracking beacon beams picked up by sensors in unmanned underwater sea craft vehicles being approached, for steered propulsion thereof into rammed hook attachment to the cages. A sea craft vehicle thereby releasably attached to a cage, is towed onboard the retrieval ship by storage reel-in of the tow line, which is then disconnected from the cage and the retrieved vehicle for subsequent use in retrieval of other unmanned sea craft vehicles.
U.S. Pat. No. 7,505,366 (issued Mar. 17, 2009) to Blackmon et al, discloses a linear mechanism for optical-to-acoustic energy conversion for optoacoustic communication from an in-air platform to an undersea vehicle. Signals used in underwater acoustic telemetry applications are capable of being generated through the linear optoacoustic regime conversion process. A number of issues concerning linear optoacoustic communication is addressed that lead to a formulation of a linear regime optoacoustic communication scheme. The use of oblique laser bean incidence at an air-water interface to obtain considerable in-air range from the laser source to the vehicle is also addressed. The effect of oblique incidence on in-water range is addressed as well. Optimum and sub-optimum linear optoacoustic sound-generation techniques for selecting the optical wavelength and signal frequency for optimizing in-water range are identified. Optoacoustic techniques employing M-ary frequency shift keying and multifrequency shift keying are compared with communication parameters such as bandwidth, data rate, range coverage and number of lasers employed.
United States Patent Publication No. 2006/0083111 (published Apr. 20, 2006) to Grasso, discloses a method for detecting, tracking and locating submarines that utilizes pulsed coherent radiation from a laser that is projected down through a water column, with particles in the water producing speckle from backscatter of the random particle distribution, with correlation of two closely time-spaced particle-based speckle patterns providing an intensity measurement indicative of the presence of a submarine. Subsurface submarine movement provides a subsurface wake which causes movement of particles such that two closely-spaced “snapshots” of the returns from particles in the same water column can detect particle movement due to the wake. The magnitude of the speckle pattern change indicates particle movement. In one embodiment, the return signals are imaged onto an intensified CCD or APA array that capture two successive laser pulses through the utilization of dual pixel registered cameras. Note that in the subject system, phase information is converted to measurable intensity information relating to particle motion.
United States Patent Publication No. 2008/0289558 (published Nov. 27, 2008) to Montgomery, discloses a profile scanner for locating a target zone on a profile of a vessel comprising an emitter adapted to progressively or instantaneously radiate towards the vessel; a receiver providing a signal indicative of radiation incident thereon; a controller or processor including stored instructions, for energizing the emitter and receiving the signal, and adapted to determine the vertical location of the target zone relative to scanner. All laser beams propagate in-air and are meant to assist surface vessels to dock to a stationary mooring on a pier to accommodate the tidal sea variation.
United States Patent Publication No. 2008/0302292 (published Dec. 11, 2008) to Ruggaber, discloses a method and apparatus for optical and autonomous docking of an underwater vehicle into a torpedo tube of a submarine. The apparatus has a moveable tube provided with an insertion/extraction device at one of its ends. The device is in the form of a tube or of a ring in a retracted state and in the form of a funnel in an extended state.
The above-cited prior art does not adequately disclose an optical docking system which is suitable for long range and short range docking of UUVs with a submarine. Consequently, those skilled in the art will appreciate the present invention that addresses the above and other problems.